Infectious Neurological Disorders

Question 1

Encephalitis

Answer 1

• Definition:
  
  • inflammation of the brain parenchyma
• Etiology:
  
  • arboviruses, HSV-1 (most common), HSV-2, HZV, EBV, CMV, rabies,West nile virus
  • HSV Encephalitis:
    
    • lesions limited to the temporal lobe, necrotizing encephalitis
• S/sxs:
  
  • -Alteration of consciousness
  • -Focal neurologic deficits: hemiparesis, sensory deficits, CN palsies
  • -Seizures,
  • -Fever
  • -HA
  • -Change in personality: hallucinations & bizarre behavior may precede neurological deficits
• PE:
  
  • HSV Encephalitis:
    
    • -Dysphagia
    • -Seizures
  • West Nile Virus Encephalitis:
    
    • -Flaccid paralysis with a clear sensorium
• Dx:
  
  • -MRI/CT: medial temporal & inferior frontal grey matter involvement
  • -EEG: asymmetric sharp waves
  • -Lumbar puncture: normal glucose, lymphocytes, elevated RBCs
  • -PCR testing: HSV identification
  • **Neuroimaging must be done!!
• Tx:
  
  • HSV: IV acyclovir x 14 days

Question 2

Brain Abscess

Answer 2

• Definition:
  
  • a localized, walled-off collection of pus surrounded by a fibrous capsule within the brain parenchyma
• Etiology:
  
  • bacteria (most common), fungi, protozoa; NO viruses
• Predisposing Factors:
  
  • otitis media, sinusitis, dental infection, trauma, neurosurgery, neutropenia, HIV infx
• S/sxs:
  
  • focal neuro deficits
• Dx:
  
  • head CT
• Tx:
  
  • Abx: Ceftriaxone + metronidazole + vancomycin
  • -If prior neurosurgical patient → get MRSA coverage
  • -Steroids: only if cerebral edema
  • -Neurosurgery consult for possible drainage.

Question 3

Bacterial Meningitis

Answer 3

• Definition:
  
  • bacterial infection of the meninges
• Etiology:
  
  • May be bacterial, viral, or subacute
  • -Strep Pneumoniae: most common cause in adults & young kids, G+ cocci
  • -Neisseria meningitidis:Most common in older children (10-19yo), G- diplococci
  • -Group B Strep: most common neonates
  • -Listeria monocytogenes: increased incidence neonates & infants, risk for preggos
  • -Haemophilus influenzae: reduced d/t HIB iz, G- coccobacillus
• Risks:
  
  • age (babies), large group gatherings (college) microbiologists, travel (sub-saharan African, mecca)
• S/sxs:
  
  • Clinical Triad:
    
    • -Fever
    • -Headache
    • -Nuchal Rigidity
  • -decreased LOC
  • -Seizures
  • -Increased intracranial pressure
  • -photosensitivity
  • -Bulging fontanelles in babies
  • Meningismus:
    
    1. Nuchal Rigidity (stiff neck)
    2. Photophobia
    3. Headache
• PE:
  
  • Brudzinski: neck flexion produces knee/hip flexion
  • -Kernig: inability to extend the knee/leg with hip flexion
• Dx:
  
  • -CSF: PMN leukocytosis, decreased glucose, increased protein, increased opening pressure, turbid
  • -CSF pathogen panels: tests for the 14 most common pathogens
  • -Cultures, empirical therapies, neuroimaging
  • *Work-up order: blood cultures, steroids, abx, CT, LP
• Tx:
  
  • Broad Spectrum Abx: Vanco + Ceftriaxone +/- dexamethasone
  • -Droplet precautions for 24 hours
  • -Post-exposure prophylaxis: Ciprofloxain or Rifampin
  • -Listeria: addampicillin; prevent by cooking foods & pasteurizing dairy products

Question 4

When does a CT scan NOT have to be done before a lumbar puncture in meningitis?

Answer 4

• CT scan doesn’t have to be done before LP if < 60yo,
• immunocompetent,
• no hx of CNS disease,
• no recent seizure,
• normal sensorium & cognition,
• no recent major trauma,
• no papilledema

Question 5

Viral Meningitis

Answer 5

• Etiology:
  
  • Enteroviruses, varicella-zoster, HSV2, Epstein-Barr Virus, Arthropod-borne viruses
• S/sxs:
  
  • Clinical Triad:
    
    1. Fever
    2. Headache
    3. Nuchal Rigidity
• PE:
  
  • Decreased LOC, malaise, myalgias, anorexia, n/v/d, abd pain
• Dx:
  
  • CSF exam: lymphocytes,normal glucose & protein, clear
  • -viral culture
  • -Serologic studies

Question 6

Subacute Meningitis

Answer 6

• Etiologies:
  
  • M. Tuberculosis, C. neoformans, H. capsulatum, C. immitis, T. Palladium
• S/sxs:
  
  • -low-grade fever
  • -headache
  • -nuchal rigidity
  • -Lethargy

Question 7

Aseptic Meningitis

Answer 7

• Definition:
  
  • clinical & lab evidence of meningitis where the organisms are not detected in the CSF
• Etiologies:
  
  • viral (enteroviruses most common), bacteria, parasitic, drugs, autoimmune, malignancy, post-infectious
• S/sxs:
  
  • *Classic sxs of meningitis but may be milder
  • -Fever
  • -HA
  • -Nuchal rigidity
• Dx:
  
  • Dx of exclusion. R/o bacterial meningitis
  • CSF: normal glucose, lymphocyte
• Tx:
  
  • supportive: antipyretics, IV fluids, analgesics